Hydraulic transmitter



Nov. 13, 1951 R. STEVENSON Y 2,575,319

HYDRAULIC TRANSMITTER Filed June 17, 1946 A 2.SHEETS-SHEET 1 IN V ENTOR.

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1951 R. STEVENSON HYDRAULIC TRANSMITTER 2 SHEETS-SHEET 2 Filed June 17, 1946 INVENTOR. fiae/f Sfe Venso/z A T TOR NEvs.

Patented Nov. 13, 1951 HYDRAULIC TRANSMITTER Robert Stevenson, Barrington, R. I., assignor to Merit Engineering, Inc., a corporation of Rhode Island Application June 17, 1946, Serial No. 677,371

1 Claim. (01. sin-54.6)

This invention relates to a hydraulic control system and more particularly to the hydraulic transmitter for the system.

In the transmittin of liquid for the hydraulic control of movable parts, the pressure in the transmitter has been rather critical and if the fluid was not exactly properly proportioned to the hand operated lever, considerable pressures were developed, making the hand operation of the system difiicult.

One of the objects of this invention is to provide an arrangement so. that the same amount of pressure will be present in the hydraulic system at all times and the movement of the handle for manipulating the liquid in thesystem will be uniform. Another object of the invention, is to provide a system in which there maybe expansion of the liquid used without affecting the operation of the system. 1

Another object of the invention isto provide an expansion chamber in the operating system upon which a constant pressure is provided and which will permit of considerable change in volume of the liquid utilized without materially changing the pressure in the system.

Another object of the invention is to utilize the expansion chamber to some extent to supply any losses of liquid in the system which may be small so that the system will continue to function with varying volumes of liquid therein at substantially the same resistance to hand pres trated in Figs. 1 and 2.

The complete system in which this invention is used is illustrated in my co-pending application, Ser. No. 541,449, now abandoned, in which I have illustrated a transmitter unit in the lower part of Fig. 1. This transmitter unit consists of cylinders in which pistons are mechanically moved by hand pressure in reverse relation so that if one piston is moved downwardly, the other piston is moved upwardly so as to transmit liquid along crating parts at a distance.

. 2 certain conduits to apply pressure to some op- Each of these flow lines is .a complete system in itself and I have provided an expansion chamber which comm-uni cates with each of the flow lines at a point where the communication will not be cut off by the piston'so that the system is maintained under substantially the pressure of a spring in the expansion chamber which pressure is sufiicient to move the operating parts which the transmitter controls.

With reference to the drawings, l0 designates generally a block which is provided with a pluralityj of bores, there being the bores H, and I2 located in close adjacency which open into larger threaded bores l3 and M which are closed by plugs l5 and It having conduits l1 and I8 therein which are used for the transmission of liquid to'the point of use. Pistons l9 and 28 are slidable in the bores H and I2, each having stems 2| and 22 extending out of the bores at their opposite ends for the reception of operating pressures. Springs 23 and 24 surround the stems 2| and 22 and serve as a cushion for the movement of the pistons to project the stems out of the bores at one end thereof. Vent holes 25 and 26 are provided to prevent trapping of air beneath the pistons.

The body It has a pair of arms 21 and 28 which extend upwardly therefrom and which serve tov rotatably hold a shaft 29. The shaft has cams 30 and 3| mounted thereon in a plane so as to engage the ends of the stems 2| and 22. vA handle 30 having a knob 3| extends laterally from the shaft 29 and this handle engages a stop 32 on one side and a stop 33 on the other side so as to provide a movement of the shaft through substantially degrees. The cams 3G and 3! are oppositely arranged so that as the cam 3Q forces the stem 2| and piston l9 downwardly in the chamber H, the cam 3! is raised so as to permit the stem 22 and piston 20 to move upwardly-in the chamber l2 by the action of the reverse flow of fluid in the system. Each flow line is maintained full of liquid and the liquid is moved in one direction, as above described, by the pistons l9 and 2G and in the reversedirection by the work acted upon when either of the pistons are released from engagement with the cams 3i! and 3!. The work controlled may be a plurality of valves as set forth in my co-pending application, above referred to.

In order to provide an expansion chamber, I have provided bores 34 and 35 in the body Ill which have plungers 36 and 31 slidably mounted V therein. The upper ends of these bores are enlarged and threaded as at 38 and 39 for the reception of caps 40 and 4| which provide a long container for springs 42 and 43 which have abutment and closure means 44 and 45 at the upper end of these caps. These caps are reduced and threaded at their lower ends to engage the threads 38 and 39L"I1i"order to provide communication between-these chambers 34 and 35, I have pro vided conduits 4B and 41 which extend to the junction between the cylinders H and I2 and con'=- duits l1 and IB. These conduits 46 and-41-1are usually provided by bores from the sides ofthe body and are closed by headed screwsiqandi I: at the ends of these bores. r iii The tension of the springs 42 and 43 determines the pressure which will exist in each of the systems. Should expansion occur these springs may be somewhat compressed but will remain 'at-sulf stantially the same pressure. Should contraction occur or "leakage occur in the system, the s'pringswill force the plungers downwardly so that substantially the same pressure is Lmaintained. Thus theresistance to the movement of the handle on the pistons 9 and -20. which moves the? cams will be m'aintained substantially the same and'liquid will be transmitted along the conduits I! as the piston 59 is moved downward lywhile as the cam is moved to free the piston Ml-the fluid will flow in the "other direction to push the piston 29 upwardly and follow:1the cafn surface until stopped by the spring 24.

Iclaimr i A hydraulic transmitter comprising a solid block having a pair of cylindrical bores each closed at one end by a wall of the block, closure means including a transmission conduit at the other end ofeach bore,a piston in each bore having a stem extending axially out of the bore through the said wall'of the blocki a springin each bore encircling each stem and acting between said Well and'pis ton to urge the piston in one direction, a shaft in the plane of said stems extending laterally of the axes of said stems, a pair of similar cams fixed on said shaft so that when the surface of one moves toward one stem the surface of the other moves away from the other stem, a handle on said shaft and stops limiting movement of 'saidhandle in opposite directions through 180 degrees, said block also having a'pair of expansion chambers therein, one bore being connected in all positions of the piston therein with one chamberand the other bore being connected in all positions of the piston therein with the other chamber, a'plunger in-each chamber and a spring actingoneach plunger to exert a pressure on the liquid in the chamber, bore and conduit system to maintains. substantially constant pressure therein.

ROBERT STEVENSON.

REFERENCES CITED Theiollowing references are of record in the file of this patent:

NITEDsTATEs PATENTS Number V Date 

